Elastic roller

ABSTRACT

An elastic roller includes: a roller shaft; and an elastic member. The elastic roller includes an inner layer side elastic member, and a coating layer. The inner layer side elastic member has a rubber hardness of 30 to 80 degrees that is measured by a durometer type A in accordance with the standard of JIS K 6253. The inner layer side elastic member has a tear strength of 25 N/mm or more that is measured using an unnicked angle-shaped test piece in accordance with JIS K 6252. The coating layer is made of silicone resin, and has a thickness of 10 to 100 μm. The silicone resin has hardness of 20 degrees or less that is measured using a spring-based Asker C type in accordance with SRIS 0101 standard. The inner layer side elastic member has a plurality of internal grooves along a circumferential direction. Each of the internal grooves has a width of 25 to 1,300 μm, and has a depth of 25 to 500 μm. Each of the internal grooves has a V-shaped in cross section and has a groove angle of 50 to 120 degrees.

TECHNICAL FIELD

The present invention relates to elastic rollers.

BACKGROUND ART

Conventionally a linerless label has been developed. The linerless labeldoes not include a sheet to be separated (a so-called liner). The sheetis temporarily attached to the rear face of an adhesive layer of thelabel. Such a linerless label is expected to be a resource-savingmaterial because it does not have a liner that will be discarded afteruse (see Laid open patent publication JP 2011-31426 A, for example).

FIG. 5 is a perspective view of a conventional linerless label 1 that iswound into a roll. As shown in FIG. 5, this linerless label 1 includes alabel base 2, an adhesive layer 3 on the rear-face side, athermosensitive color developing layer 4 on the front-face side, and atransparent separation agent layer 5 on the top of these layers.

The label base 2 has a location detection mark 6 preprinted on the rearface.

The label base 2 may have fixed information (not illustrated) preprintedon the surface as needed. The fixed information may be a mark indicatingthe label user, the name, and/or other designs.

This linerless label 1 may be separated into a single label piece 1A bycutting it at cutting lines 7 at predetermined intervals.

FIG. 6 is a schematic side view of a conventional thermal printer 8. Thethermal printer 8 has a function of printing variable information on thelinerless label 1. Variable information may be information on acommodity information, such as the price and a barcode, or managementinformation on goods or services, for example. The thermal printer 8includes a feed part 9, a guide part 10, a detection part 11, a printpart 12, and a cutting part 13.

The feed part 9 is configured to hold a roll-shaped linerless label 1and to release the linerless label 1 in a belt-shaped toward the guidepart 10, the detection part 11, the print part 12 and the cutting part13.

The guide part 10 includes a guide roller 14. Such a guide part 10 isconfigured to guide the released linerless label 1 toward the detectionpart 11 and the print part 12.

The detection part 11 includes a location detection sensor 15. Thedetection part 11 is configured to detect a location detection mark 6 onthe rear face of the linerless label 1 so as to detect the location ofthe linerless label 1 (label piece 1A) relative to the print part 12.

The print part 12 includes a thermal head 16 and a platen roller 17. Theprint part 12 is configured to pinch the linerless label 1 between thethermal head and the platen roller with a predetermined print pressure.The print part 12 is configured to rotary-drive the platen roller 17 ata fixed speed. The print part 12 is configured to supply print data tothe thermal head 16 to let the thermosensitive color developing layer 4develop colors. In this way, the print part 12 can print predeterminedvariable information on the linerless label 1 (label piece 1A).

The cutting part 13 includes a fixed blade 18 and a movable blade 19.The cutting part 13 is configured to cut the printed linerless label 1at a part corresponding to the cutting lines 7 at predeterminedintervals when the linerless label 1 is transferred between theseblades, and to eject the label pieces 1A.

In the thermal printer 8 having such a configuration, the platen roller17 to transfer the linerless label 1 for printing is a roller made of anelastic body such as rubber member, for example. In order to avoidsticking of the adhesive of the adhesive layer 3 to the roller, such aroller may be made of a silicone rubber member having non-stick propertyor a rubber member impregnated with silicone oil. Silicone oil may beapplied to the peripheral surface of the platen roller 17 for thispurpose.

SUMMARY OF THE INVENTION Technical Problem

For a long-term use, however, it is difficult to completely prevent thesticking of the adhesive. When such sticking occurs, the linerless label1 passing through the platen roller 17 may stick to the platen roller 17and may be caught in there (see the virtual line in FIG. 6). This causesa paper jam, which will be an obstacle to the normal transferring andprinting of the linerless label 1 and ejection of label pieces 1A.

If the printer stops printing and ejection while leaving the linerlesslabel 1 pinched between the thermal head 16 and the platen roller 17,then it will be hard to separate the linerless label 1 from the surfaceof the platen roller 17. In such a case as well, the linerless label 1will be easily caught in the platen roller similarly to the above.

This leads to the necessity of repeatedly performed maintenanceoperations (e.g., cleaning of the peripheral surface of the platenroller 17, or replacing the platen roller 17 with a new one). Therefore,there is a demand for an elastic roller enabling stable transferring andprinting for a long time.

In some configurations of the printer, an elastic roller for labelshaving excellent non-stick property or separation property (releaseproperty) is required for rollers other than the platen roller 17 aswell. They include a nip roller unit (not illustrated) including a pairof rollers that is rotary-driven to transfer the linerless label 1 and aroller configured to simply guide the linerless label 1 as in the guideroller 14.

There is a demand for an elastic roller configured to stably transferthe linerless label 1 and a label with a liner when any one of them isloaded. That is, an elastic roller that can be used for transferringboth of the linerless label and the label with a liner also is demanded.

In order to avoid sticking of the adhesive layer 3, grooves are formedon the outer surface of the platen roller 17, for example, in a trialbasis so as to reduce the contact area with the linerless label 1 (withthe adhesive layer 3). However, when a typical label with a liner istransferred and printed using such a platen roller with grooves, anecessary frictional force (gripping force) cannot be obtained with theliner of the label because of the insufficient contact area with therear face of the liner. This often causes a problem about thetransferring function, such as slipping of the label, and stabletransferring and printing cannot be expected.

Such grooves or the like formed in the platen roller 17 lead to easywear of the platen roller 17 as well.

Similarly to the linerless label 1 as stated above, these problems mayoccur also when transferring or guiding a belt-shaped member made ofpaper or film having an adhesive layer or a bonding layer on the rearface or an adhesive product such as adhesive tape. Therefore, an elasticroller having excellent non-stick property or separation property(release property) is required.

The present invention aims to provide an elastic roller having excellentnon-stick property or separation property (release property) andoffering a necessary frictional force (gripping force) with abelt-shaped member.

Solution to Problem

An elastic roller according to one aspect of the present invention,comprises: a roller shaft; and an elastic member attached around theroller shaft, the elastic roller configured to transfer a belt-shapedmember while the belt-shaped member is in contact with the elasticmember. The elastic member includes: an inner layer side elastic memberdisposed around the roller shaft; and a coating layer disposed aroundthe inner layer side elastic member, the coating layer for being incontact with the belt-shaped member. The inner layer side elastic memberhas a rubber hardness of 30 to 80 degrees, the rubber hardness beingmeasured by a durometer type A in accordance with the standard of JIS K6253. The inner layer side elastic member has a tear strength of 25 N/mmor more, the a tear strength being measured using an unnickedangle-shaped test piece in accordance with JIS K 6252. The coating layeris made of silicone resin, and has a thickness of 10 to 100 μm. Thesilicone resin has hardness of 20 degrees or less, the hardness beingmeasured using a spring-based Asker C type in accordance with SRIS 0101standard. The inner layer side elastic member has a plurality ofinternal grooves along a circumferential direction. Each of the internalgrooves has a width of 25 to 1,300 μm. Each of the internal grooves hasa depth of 25 to 500 μm. Each of the internal grooves has a V-shaped incross section and has a groove angle of 50 to 120 degrees.

The silicone resin may comprise a thermosetting silicone resin.

The inner layer side elastic member may comprise a thermoplastic elasticmaterial or a thermosetting elastic material.

The coating layer may have a plurality of coating layer grooves along acircumferential direction.

The inner layer side elastic member may have an inner layerplatform-shaped apex part between neighboring internal grooves.

The coating layer may have a flat coating layer platform-shaped apexpart between neighboring coating layer grooves.

The internal grooves may desirably have a pitch of 500 to 1,500 μm.

The elastic roller may have a constant diameter in a plane orthogonal toan axial direction of the roller shaft.

The elastic roller may have a diameter in a plane orthogonal to an axialdirection of the roller shaft, the diameter gradually decreasing from acenter part of the roller shaft toward both ends of the roller shaftalong the axial direction of the roller shaft.

The elastic roller may have a diameter in a plane orthogonal to an axialdirection of the roller shaft, the diameter of a first end of the rollershaft in the axial direction thereof being different from that of asecond end in the axial direction of the roller shaft in the axialdirection thereof.

The inner layer side elastic member desirably has a tear strength of 27to 45 N/mm.

Advantageous Effects

The present invention can provide an elastic roller having excellentnon-stick property or separation property (release property) andoffering a necessary frictional force (gripping force) with abelt-shaped member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a platen roller 30 of a firstembodiment.

FIG. 2 is an enlarged cross-sectional view of a major part of the platenroller 30 in FIG. 1 along the axial direction.

FIG. 3 is a perspective view of a platen roller 40 of a secondembodiment.

FIG. 4 is a perspective view of a platen roller 50 of a thirdembodiment.

FIG. 5 is a perspective view of a conventional linerless label 1 that iswound into a roll.

FIG. 6 is a schematic side view of a conventional thermal printer 8.

DESCRIPTION OF EMBODIMENTS

(First Embodiment)

Referring to FIGS. 1 and 2, the following describes an elastic roller ofa first embodiment in the case that a platen roller 30 (elastic rollerfor labels) in the thermal printer 8 is similarly to the platen roller17 (FIG. 6). Like numbers indicate like components in FIGS. 5 and 6, andtheir detailed descriptions are omitted.

FIG. 1 is a perspective view of the platen roller 30 of a firstembodiment. FIG. 2 is an enlarged cross-sectional view of a major partof the platen roller 30 in FIG. 1 along the axial direction. As shown inFIGS. 1 and 2, the platen roller 30 includes a roller shaft 21, and anelastic member 22. The elastic member 22 is mounted around the rollershaft 21 and is rotatable integrally with the roller shaft. The platenroller 30 is configured to transfer a label (e.g., the linerless label 1in FIG. 5) while the elastic member 22 is in contact with the label.

The elastic member 22 includes an inner layer side elastic member 23that is round-pillar shaped and disposed around the roller shaft 21, anda coating layer 24 (external elastic member) that is disposed integrallywith and around the inner layer side elastic member 23. The coatinglayer 24 is in contact with the linerless label 1. The platen roller 30has grooves formed on the surface thereof.

Materials of these members are described. The inner layer side elasticmember 23 is made of a thermoplastic elastic material or a thermosettingelastic material.

Examples of synthetic resins making up the inner layer side elasticmember include polyethylene, polypropylene, polymethylpentene,polybutene, crystalline polybutadiene, polybutadiene, styrene-butadieneresin, polyvinyl chloride, polyvinyl acetate, polyvinylidene chloride,ethylene-vinyl acetate copolymer, ethylene-propylene copolymer,ethylene-propylene-diene copolymer, ionomer, polymethylmethacrylate,polytetrafluoroethylene, ethylene-polytetrafluoroethylene copolymer,polyacetal(polyoxymethylene), polyamide, polycarbonate, polyphenyleneether, polyethylene terephthalate, polybutylene terephthalate,polyarylate, polystyrene, polyethersulfone, polyimide, polyamide-imide,polyphenylene sulfide, polyoxybenzoyl, polyether ether ketone,polyetherimide, polystyrene, polyurethane, polyester, 1,2-polybutadiene,phenol resin, urea resin, melamine resin, benzoguanamine resin, diallylphthalate resin, alkyd resin, epoxy resin, and silicon resin.

Other examples that can be used include thermosetting elastic materials,such as thermosetting silicone rubber, one-component RTV (RoomTemperature Vulcanizing) rubber, two-component RTV rubber, LTV (LowTemperature Vulcanizable) silicone rubber, and oil-resistantthermosetting rubber. In particular, millable type silicone rubber ispreferable.

The inner layer side elastic member 23 has hardness of 30 to 80 degrees.The hardness is measured by a durometer type A in accordance with thestandard of JIS K 6253, and hereinafter this is called “JIS-A hardness”.

If JIS-A hardness is less than 30 degrees, such a platen roller 30 istoo soft to transfer and guide a belt-shaped member such as thelinerless label 1. That is, the platen roller 30 has a problem about thetransferring function because of excessive frictional force when contactis made. Print quality of the thermal printer 8 (FIG. 6) alsodeteriorates.

If JIS-A hardness exceeds 80 degrees, such a platen roller 30 is toohard. The transferring force and the transferring accuracy of the platenroller 30 deteriorate because of a small gripping force.

JIS-A hardness is the standard corresponding to ISO-7619-1 and ASTM D2240.

All of the contents of JIS K 6253 standard, ISO-7619-1 standard and ASTMD 2240 standard are incorporated herein by reference.

The inner layer side elastic member 23 has a tear strength of 25 N/mm ormore by the tearing test in accordance with JIS K 6252. This tearingtest is performed using an unnicked angle-shaped test piece. If the tearstrength is less than 25 N/mm, sufficient durability cannot be obtained.Although larger tear strength is desirable, if merely tear strength isincreased, other physical properties, such as hardness and stretch, maybe degraded. The upper limit of the tear strength is limited to about 50N/mm. Considering a good balance of the properties, the tear strength of27 to 45 N/mm is desirable.

The tearing test in accordance with JIS K 6252 (tearing test using anunnicked angle-shaped test piece) is the standard corresponding to ISO34-1 and ISO 34-2.

All of the contents of JIS K 6252 standard, ISO 34-1 standard and ISO34-2 standard are incorporated herein by reference.

The coating layer 24 is made of a thermosetting silicone resin or othersilicone resins having JIS-C hardness of 20 degrees or less. JIS-Chardness is measured using a spring-based Asker C type in accordancewith SRIS 0101 standard.

Examples of the silicone resin include silicone resin called siliconegel, RTV (Room Temperature Vulcanizing) liquid silicone rubber, LTV (LowTemperature Vulcanizable) liquid silicone rubber, ultraviolet cureliquid silicone rubber, and thermosetting liquid silicone rubber.

Silicone resins inherently have non-stick property or separationproperty. Therefore, when the linerless label 1 is pressed to andtransferred using a roller made of silicone resin, the adhesive layer 3of the linerless label 1 does not stick to the silicone resin.

A thermosetting silicone resins are relatively easy to adjust thethermosetting conditions, process and set JIS-C hardness.

If JIS-C hardness is 20 degrees or less, such a silicone resin is a gelthat is appropriately soft. It has a frictional force (gripping force)required with a belt-shaped member such as the linerless label 1 or alabel with a liner, and resists wear well.

Therefore, the platen roller 30 made of the resin has a separationproperty and a gripping force required with a belt-shaped member such asthe linerless label 1 or a label with a liner, and can exert stabletransferring and guiding functions.

If JIS-C hardness exceeds 20 degrees, elasticity of the coating layer 24is close to the elasticity of a rubber member. Then adhesiveness of thecoating layer 24 on the surface increases rapidly, and the layer wearsdown easily.

The hardness (JIS-C hardness) measured using a spring-based Asker C typein accordance with SRIS 0101 standard is globally used as a de factstandard to measure low degree of hardness, and is equivalent to JIS K7312.

All of the contents of SRIS 0101 standard and JIS K 7312 standard areincorporated herein by reference.

The coating layer 24 has a thickness T (FIG. 2) of 10 to 100 μm.

If thickness T is less than 10 μm, the coating layer 24 hasnon-uniformity in thickness. Therefore, it is difficult to have stableseparation property and gripping force.

If thickness T exceeds 100 μm, the layer is brittle as the coating filmof the inner layer side elastic member 23 in the platen roller 30, andis easily torn.

Referring next to FIGS. 1 and 2, the following describes grooves on thesurface of the platen roller 30. The platen roller 30 has a plurality ofinternal grooves 31 having a V-shaped in cross section along acircumferential direction of the inner layer side elastic member 23(made of thermosetting silicone rubber having JIS-A hardness of 50degrees). More precisely, the cross section is taken along in the planeincluding the center line of the platen roller 30. The platen roller 30has the coating layer 24 made of a thermosetting silicone resin havingJIS-C hardness of 15 degrees. The coating layer 24 is formed around theinner layer side elastic member 23 with the internal grooves 31.

The inner layer side elastic member 23 has an inner layerplatform-shaped apex part 32 between the neighboring internal grooves31.

The coating layer 24 formed around the inner layer side elastic member23 has a plurality of coating layer grooves 33 at the positions of theinternal grooves 31. The coating layer grooves 33 are along acircumferential direction of the coating layer 24. Each coating layergroove 33 has a substantially V-shaped in cross section (see FIG. 2).

The coating layer 24 has a flat coating layer platform-shaped apex part34 between the neighboring coating layer grooves 33.

The internal grooves 31 and the coating layer grooves 33 may have shapesin cross section other than a V-shaped, such as a U-letter shape, atruncated conical shape, a rectangular shape and other polygonal shapes.

The internal grooves 31 have a pitch P of 500 to 1,500 μm.

If the pitch P of the internal grooves 31 is less than 500 μm, there islittle space for processing the inner layer platform-shaped apex part 32between mutually neighboring internal grooves 31.

If the pitch P of the internal grooves 31 exceeds 1,500 μm, it tends todecrease the ratio of the internal grooves 31 or the coating layergrooves 33 to a whole of the platen roller 30, and to increase thecontact area with a belt-shaped member such as the linerless label 1.This may lead to a reduction in separation property of the platen roller30.

The internal grooves 31 has a width W of 25 to 1,300 μm, preferably 50to 500 μm.

If the width W of the internal grooves 31 is less than 25 μm, thecontact area with a belt-shaped member such as the linerless label 1increases. It tends to reduce separation property of the platen roller30.

If the width W of the internal grooves 31 exceeds 1,300 μm, pressure ata part of the platen roller 30 to appropriately press and support thelinerless label 1 on the side of the adhesive layer 3 decreases. Thenmissing part to be printed on the label piece 1A tends to occur at theprint part 12 of the thermal printer 8, that is, print accuracydeteriorates.

The internal grooves 31 have a depth H of 25 to 500 μm, preferably 50 to400 μm.

If the depth H of the internal grooves 31 is less than 25 μm, thecontact area with a belt-shaped member such as the linerless label 1increases. It tends to reduce separation property of the platen roller30.

If the depth H of the internal grooves 31 exceeds 500 μm, pressure at apart of the platen roller 30 to press and support the linerless label 1on the side of the adhesive layer 3 decreases. Then missing part to beprinted on the label piece 1A tends to occur at the print part 12 of thethermal printer 8, that is, print accuracy deteriorates.

The internal grooves 31 have a groove angle G of 50 to 120 degrees,preferably 60 to 100 degrees.

If the groove angle G of the internal grooves 31 is less than 50degrees, the contact area with a belt-shaped member such as thelinerless label 1 increases. It tends to reduce separation property ofthe platen roller 30.

If the groove angle G of the internal grooves 31 exceeds 120 degrees,pressure at a part of the platen roller 30 to press and support thelinerless label 1 on the side of the adhesive layer 3 decreases. Thenmissing part to be printed on the label piece 1A tends to occur at theprint part 12 of the thermal printer 8, that is, print accuracydeteriorates.

The following describes a rolling angle test to evaluate non-stickproperty (separation property) of the elastic roller of the presentembodiment.

The linerless label 1 of FIG. 5 is fixed on a flat and even base plateso that the adhesive layer 3 is directed upward. For adhesive as thereference in the test, an emulsion adhesive having strong adhesivenessis used. The adhesive has a thickness of 20 μm.

The platen roller 30 to be tested is placed on the adhesive layer 3.Then a weight of 2 Kg in weight is placed thereon to apply the weight tothe platen roller for 15 seconds to make the platen roller 30 stick tothe linerless label 1.

After 15 seconds, the weight is removed, and the base plate is inclinedby gradually raising one end of the base plate that is parallel to theaxial line of the platen roller 30 while fixing the other end of thebase plate.

When the platen roller 30 starts to roll downward, the raising of thebase plate is stopped. Then, the inclination angle of the base plate atthis time is measured. Such an inclination angle is the rolling angle.

A platen roller 30 having a smaller inclination angle (rolling angle)and rolling easily has high non-stick property. Such platen roller 30 issuitable to transfer the linerless label 1.

An experiment by the present inventor showed that there are no problemsin the actual operation as rollers such as the platen roller 17 in thethermal printer 8 (FIG. 6) or a nip roller if an elastic roller has thisrolling angle of 30 degrees or less, preferably 15 degrees or less aftertransferring the linerless label 1 for the distance of 20 Km(Kilometers).

An experiment to transfer the linerless label 1 and a label with a linerwas performed using the thus configured platen roller 30.

For a first embodiment, a platen roller 30 was prepared, including theinner layer side elastic member 23 made of silicone rubber having JIS-Ahardness of 50 degrees and the tear strength of 36 N/mm. The coatinglayer 24 around the inner layer side elastic member had a thickness T of50 μM, and was made of thermosetting silicone rubber (silicone gel)having JIS-C hardness of 15 degrees. The internal grooves 31 had thepitch P of 750 μm, the width W of 410 μm, the depth H of 350 μm and thegroove angle G of 60 degrees.

For comparison, a platen roller (comparative roller) including anelastic member only made of silicone rubber having JIS-A hardness of 45degrees and the tear strength less than 25 N/mm was prepared. Thisplaten roller had the internal grooves 31 only having similar dimensionsas those stated above, but did not have the coating layer 24. Theexperiment was performed to transfer the linerless label 1 and a labelwith a liner using this platen roller.

After transferring the linerless label 1 for 20 Km using the platenroller 30 of this embodiment, the rolling angle of the platen roller 30was measured by the method as stated above. The measurement was lessthan 13 degrees. Similarly, the rolling angle measured after normallytransferring the label with a liner for 20 Km was less than 9 degrees.From both of the measurements, the platen roller as the elastic rollerwas sufficient in separation property to transfer the linerless labeland in gripping force to transfer the label with a liner.

After transferring the linerless label 1 for 20 Km, the wear proceedingrate of the platen roller 30 was 0.05% or less. After transferring alabel with a liner for 50 Km, the wear proceeding rate of the platenroller 30 was 0.5% or less. It was found that the platen roller 30 hadsufficient wear resistance. Synergistic effect was confirmed such thatdurability such as wear resistance was obtained using silicone rubberhaving JIS-A hardness of 50 degrees and the tear strength of 36 N/mm asthe inner layer side elastic member 23 and separation property wasobtained using a thermosetting silicone resin (silicone gel) havingJIS-C hardness of 15 degrees as the coating layer 24 formed around theinner layer side elastic member.

The linerless label 1 was transferred using the platen roller as thecomparative roller. The comparative roller was made of silicone rubberonly having JIS-A hardness of 45 degrees and the tear strength less than25 N/mm and did not have the coating layer 24. Transferring wasperformed normally immediately after the starting of the transferringtest due to separation property of the silicone rubber itself. However,after transferring for 0.5 Km, the linerless label 1 was wound aroundthe comparative roller. When the rolling angle of the platen roller asthe comparative roller at this time was measured, the platen rollerstill stuck to the adhesive layer even where the base plate of thetester was inclined by 70 degrees. It was found that this platen rollerwas unusable for long-distance transferring. When a label with a linerwas transferred, slip occurred and transferring for a specified distancefailed. In this way, it was found that this platen roller did not have asufficient gripping force.

Further, another platen roller 30 was prepared, using the same materialsas those of a first embodiment, but the width W and the depth H of theinternal grooves 31 were changed. Then, the experiment to transfer thelinerless label 1 and a label with a liner was performed.

A coating layer 24 was formed around the inner layer side elastic member23. The coating layer 24 was made of a thermosetting silicone resin(silicone gel) having the thickness T of 50 μm and JIS-C hardness of 15degrees. The internal grooves 31 had the pitch P of 750 μm, the width Wof 87 μm, the depth H of 75 μm, and the groove angle G of 60 degrees.

A platen roller (comparative roller) including the internal grooves 31only having the same dimensions as stated above, but not including thecoating layer 24 was prepared. The experiment was performed to transferthe linerless label 1 and a label with a liner using this platen roller.

After transferring the linerless label 1 using the platen roller 30having the narrow width W and the shallow depth H of the internalgrooves 31 for 20 Km, the rolling angle of the platen roller wasmeasured by the method as stated above. The measurement was less than 18degrees. Similarly, after transferring a label with a liner for 20 Km,the measurement was less than 9 degrees. From both of the measurements,it was found that the platen roller had sufficient separation propertyto transfer a linerless label and gripping force to transfer a labelwith a liner as the elastic roller.

After transferring the linerless label 1 for 20 Km, the wear proceedingrate of the platen roller 30 was 0.05% or less. After transferring alabel with a liner for 50 Km, the wear proceeding rate of the platenroller 30 was 0.5% or less. It was found that the platen roller 30 hadsufficient wear resistance.

The linerless label 1 was transferred similarly for 1 Km using theplaten roller (comparative roller) not including the coating layer 24and including the internal grooves 31 only having the pitch P of 750 μm,the width W of 87 μm, the depth H of 75 μm, and the groove angle G of 60degrees. After that, the rolling angle test was performed. The platenroller still stuck to the adhesive layer even when the base plate of thetester was inclined by 70 degrees. It was found that this platen rollerdid not have a separation property necessary for use. When a label witha liner was transferred, slip occurred and transferring for a specifieddistance failed. In this way, it was found that this platen roller didnot have a sufficient gripping force.

A platen roller 30 (elastic roller) having the internal grooves 31 inthe inner layer side elastic member 23 as well as having the coatinglayer grooves 33 in the coating layer 24 showed both of a separationproperty and a gripping force required to transfer a linerless label anda label with a liner.

(Second Embodiment)

FIG. 3 is a perspective view of a platen roller 40 of a secondembodiment. As shown in FIG. 3, the platen roller 40 has a diameter inthe plane orthogonal to the axial direction of the roller shaft 21 thatgradually decreases from a center part to both ends along the axialdirection of the roller shaft 21. That is, this platen roller 40 has ashape such that a center part of the platen roller 30 of a firstembodiment protrudes. Other than a so-called barrel-shape, this platenroller includes the inner layer side elastic member 23 and the coatinglayer 24 making up the elastic member 22 that are made of the samematerials as those of a first embodiment. The internal grooves 31, thecoating layer grooves 33, the inner layer platform-shaped apex part 32and the coating layer platform-shaped apex part 34 are also the same asthose of a first embodiment. The difference in diameter between thecenter part and both ends of the platen roller 40 is 10 to 250 μm.

This platen roller 40 is effective for transferring a label having awidth narrower than the width of the print part 12 of the thermalprinter 8 (the widths of the thermal head 16 and the platen roller 17)and printing thereon. For instance, the effective printing width of a4-inch printer is 104 mm. If a label (either a linerless label or alabel with a liner) of 40 mm in width is set at the center of the printpart 12 of this printer for transferring and printing, the platen roller17 and the thermal head 16 rub against directly at a part not pinchingthe label therebetween. This causes an increase in load or wear at thispart. When the platen roller 40 having a protruding center part is usedfor this purpose, a contact between both ends of the platen roller 40and the thermal head 16 is reduced or they are not in contact.Therefore, transferring and printing are more stable, and the life ofthe platen roller 40 can be lengthened.

(Third Embodiment)

FIG. 4 is a perspective view of a platen roller 50 of a thirdembodiment. As shown in FIG. 4, the platen roller 50 has a diameter inthe plane orthogonal to the axial direction of the roller shaft 21 thatis not constant but is different between the diameter of a first end 50Land that of a second end 50R in the axial direction thereof. In FIG. 4,the platen roller 50 has a maximum diameter part 50M at a part close tothe second end 50R relative to the center part. The platen roller 50 hasa shape such that a thick part is placed to one side. Other than such ashape that a thick part is placed to one side, this platen rollerincludes the inner layer side elastic member 23 and the coating layer 24making up the elastic member 22 that are made of the same materials asthose of a first embodiment. The internal grooves 31, the coating layergrooves 33, the inner layer platform-shaped apex part 32 and the coatinglayer platform-shaped apex part 34 are also the same as those of a firstembodiment. The difference in diameter between the maximum diameter part50M and the first end 50L having the minimum diameter is 10 to 250 μm.

This platen roller 50 is effective for transferring a label having awidth narrower than the width of the print part 12 of the thermalprinter 8 (the widths of the thermal head 16 and the platen roller 17)while positioning the label on one side of the print part 12 andprinting thereon. For instance, the effective printing width of a 4-inchprinter is 104 mm. A label (either a linerless label or a label with aliner) of 40 mm in width is positioned on one side of the print part 12of this printer for transferring and printing. Then the label is pinchedbetween a second peripheral face 51R including the maximum diameter part50M and the thermal head, and so can be transferred and printed stably.On the contrary, a first peripheral face 51L of the platen roller doesnot pinch the label, at which the platen roller 17 and the thermal head16 rubs against directly. This platen roller 50 can reduce a contactbetween the first peripheral face 51L of the platen roller 50 and thethermal head 16 or they are not in contact. Therefore, transferring andprinting are more stable, and the life of the platen roller 50 can belengthened.

In FIG. 4, the platen roller 50 has a maximum diameter part 50M at apart close to the second end 50R relative to the center part, and thediameter gradually decreases from that position toward the first end 50Land the second end 50R. The position of the maximum diameter part 50Mand the degree of gradually decreasing are not limited to this. Thediameter from the second end 50R to the maximum diameter part 50M, i.e.,the diameter at the second peripheral face 51R may be constant, and thediameter may gradually decrease at the first peripheral face 51L only.Alternatively, the platen roller 50 may have a maximum diameter at thesecond end 50R and the diameter may gradually decrease toward the firstend 50L.

The embodiments as stated above describe an example where the elasticroller is used as a platen roller of a printer. This elastic roller maybe used as other rollers such as a guide roller and a nip roller thathave its separation property (non-stick property) and gripping property.In addition to them, this elastic roller may be used as an attaching(pressing) roller of an automatic attachment device of labels, and aguide roller, a deflecting roller and a driving roller of a printer,various coaters, and processing equipment of belt-shaped articles.

REFERENCE SIGNS LIST

-   1 linerless label-   1A label piece of linerless label 1-   2 label base-   3 adhesive layer-   4 thermosensitive color developing layer-   5 separation agent layer-   6 location detection mark-   7 cutting line-   8 thermal printer-   9 feed part-   10 part-   11 detection part-   12 print part-   13 cutting part-   14 guide roller-   15 location detection sensor-   16 thermal head-   17 platen roller-   18 fixed blade-   19 movable blade-   21 roller shaft-   22 elastic member-   23 inner layer side elastic member-   24 coating layer-   30, 40, 50 platen roller-   31 internal groove-   32 inner layer platform-shaped apex part-   33 coating layer groove-   34 coating layer platform-shaped apex part-   50L first end-   50M maximum diameter part-   50R second end-   51L first peripheral face-   51R second peripheral face-   T thickness of coating layer 24-   P pitch of internal grooves 31-   W width of internal grooves 31-   H depth of internal grooves 31-   G groove angle of internal grooves 31

The invention claimed is:
 1. An elastic roller comprising: a roller shaft; and an elastic member attached around the roller shaft, the elastic roller configured to transfer a belt-shaped member while the belt-shaped member is in contact with the elastic member, wherein the elastic member includes: an inner layer side elastic member disposed around the roller shaft; and a coating layer disposed around the inner layer side elastic member, the coating layer for being in contact with the belt-shaped member, the inner layer side elastic member having a rubber hardness of 30 to 80 degrees, the rubber hardness being measured by a durometer type A in accordance with the standard of JIS K 6253, the inner layer side elastic member having a tear strength of 25 N/mm or more, the tear strength being measured using an unnicked angle-shaped test piece in accordance with JIS K 6252, the coating layer being made of silicone resin, the coating layer having a thickness of 10 to 100 μm, the silicone resin having a hardness of 20 degrees or less, the hardness being measured using a spring-based Asker C type in accordance with SRIS 0101 standard, the inner layer side elastic member having a plurality of internal grooves along a circumferential direction, each of the internal grooves having a width of 25 to 1,300 μm, each of the internal grooves having a depth of 25 to 500 μm, and each of the internal grooves having a V-shaped in cross section and having a groove angle of 50 to 120 degrees.
 2. The elastic roller according to claim 1, wherein the silicone resin is a thermosetting silicone resin.
 3. The elastic roller according to claim 2, wherein the inner layer side elastic member is made of a thermoplastic elastic material or a thermosetting elastic material.
 4. The elastic roller according to claim 2, wherein the coating layer has a plurality of coating layer grooves along a circumferential direction.
 5. The elastic roller according to claim 4, wherein the coating layer has a flat coating layer platform-shaped apex part between neighboring coating layer grooves.
 6. The elastic roller according to claim 2, wherein the inner layer side elastic member has an inner layer platform-shaped apex part between neighboring internal grooves.
 7. The elastic roller according to claim 2, wherein the internal grooves have a pitch of 500 to 1,500 μm.
 8. The elastic roller according to claim 2, wherein the elastic roller has a constant diameter in a plane orthogonal to an axial direction of the roller shaft.
 9. The elastic roller according to claim 2, wherein the elastic roller has a diameter in a plane orthogonal to an axial direction of the roller shaft, the diameter gradually decreasing from a center part of the roller shaft toward both ends of the roller shaft along the axial direction of the roller shaft.
 10. The elastic roller according to claim 2, wherein the elastic roller has a diameter in a plane orthogonal to an axial direction of the roller shaft, the diameter of a first end of the roller shaft in the axial direction thereof being different from that of a second end of the roller shaft in the axial direction thereof.
 11. The elastic roller according to claim 2, wherein the inner layer side elastic member has a tear strength of 27 to 45 N/mm.
 12. The elastic roller according to claim 1, wherein the inner layer side elastic member is made of a thermoplastic elastic material or a thermosetting elastic material.
 13. The elastic roller according to claim 1, wherein the coating layer has a plurality of coating layer grooves along a circumferential direction.
 14. The elastic roller according to claim 13, wherein the coating layer has a flat coating layer platform-shaped apex part between neighboring coating layer grooves.
 15. The elastic roller according to claim 1, wherein the inner layer side elastic member has an inner layer platform-shaped apex part between neighboring internal grooves.
 16. The elastic roller according to claim 1, wherein the internal grooves have a pitch of 500 to 1,500 μm.
 17. The elastic roller according to claim 1, wherein the elastic roller has a constant diameter in a plane orthogonal to an axial direction of the roller shaft.
 18. The elastic roller according to claim 1, wherein the elastic roller has a diameter in a plane orthogonal to an axial direction of the roller shaft, the diameter gradually decreasing from a center part of the roller shaft toward both ends of the roller shaft along the axial direction of the roller shaft.
 19. The elastic roller according to claim 1, wherein the elastic roller has a diameter in a plane orthogonal to an axial direction of the roller shaft, the diameter of a first end of the roller shaft in the axial direction thereof being different from that of a second end of the roller shaft in the axial direction thereof.
 20. The elastic roller according to claim 1, wherein the inner layer side elastic member has a tear strength of 27 to 45 N/mm. 